Copper conductor compositions

Claim 1

A printable thick film conductor composition comprising an admixture of finely divided particles of: (a) metallic copper having an oxide coating which contains at least 0.2% by weight oxygen as a copper oxide coating, the particles having a size range of 0.5-10 μm, average particle size of 1-5 μm and a surface-to-weight ratio of less than 1 m 2 /g; (b) copper oxide having a size range of 0.1-10 μm and average particle size of 0.5-5 μm, the weight ratio of copper oxide particles to oxide-coated copper metal particles being from 0 to 0.15; (c) an inorganic binder having a softening point of 300°-700° C., a size range of 1-15 μm, the weight ratio of copper oxide in the binder to copper metal particles being from 0 to 0.5, all dispersed in (d) an organic medium containing not more than 1.0% wt. resin, basis total composition, the total oxygen content of the copper oxides of (a), (b) and (c) being sufficient to provide 1-2% by weight oxygen, basis copper, and the weight ratio of oxygen added as copper oxide in (b) and (c) to copper oxide on the copper metal particles is from 0.2 to 0.5.